Tunable coupling of a quantum phononic resonator to a transmon qubit via galvanic-contact flip-chip architecture

A hybrid system with tunable coupling between phonons and qubits shows great potential for advancing quantum information processing. In this work, we demonstrate strong and tunable coupling between a surface acoustic wave resonator and a transmon qubit based on the galvanic-contact flip-chip technique. The coupling strength varies from 2π× 7.0 to −2π× 20.6 MHz, which is extracted from different vacuum Rabi oscillation frequencies. The phonon-induced ac Stark shift of the qubit at different coupling strengths is also shown. Our approach offers a good experimental platform for exploring quantum acoustics and hybrid systems.